fs: make do_renameat2() take struct filename

Pass in the struct filename pointers instead of the user string, and
update the three callers to do the same.

This behaves like do_unlinkat(), which also takes a filename struct and
puts it when it is done. Converting callers is then trivial.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/internal.h

@@ -78,6 +78,8 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 long do_rmdir(int dfd, struct filename *name);
 long do_unlinkat(int dfd, struct filename *name);
 int may_linkat(struct path *link);
+int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
+		 struct filename *newname, unsigned int flags);
 
 /*
  * namespace.c

fs/namei.c

@@ -4346,8 +4346,8 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 }
 EXPORT_SYMBOL(vfs_rename);
 
-static int do_renameat2(int olddfd, const char __user *oldname, int newdfd,
-			const char __user *newname, unsigned int flags)
+int do_renameat2(int olddfd, struct filename *from, int newdfd,
+		 struct filename *to, unsigned int flags)
 {
 	struct dentry *old_dentry, *new_dentry;
 	struct dentry *trap;
@@ -4355,32 +4355,30 @@ static int do_renameat2(int olddfd, const char __user *oldname, int newdfd,
 	struct qstr old_last, new_last;
 	int old_type, new_type;
 	struct inode *delegated_inode = NULL;
-	struct filename *from;
-	struct filename *to;
 	unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
 	bool should_retry = false;
-	int error;
+	int error = -EINVAL;
 
 	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
-		return -EINVAL;
+		goto put_both;
 
 	if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
 	    (flags & RENAME_EXCHANGE))
-		return -EINVAL;
+		goto put_both;
 
 	if (flags & RENAME_EXCHANGE)
 		target_flags = 0;
 
 retry:
-	from = filename_parentat(olddfd, getname(oldname), lookup_flags,
-				&old_path, &old_last, &old_type);
+	from = filename_parentat(olddfd, from, lookup_flags, &old_path,
+					&old_last, &old_type);
 	if (IS_ERR(from)) {
 		error = PTR_ERR(from);
-		goto exit;
+		goto put_new;
 	}
 
-	to = filename_parentat(newdfd, getname(newname), lookup_flags,
-				&new_path, &new_last, &new_type);
+	to = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last,
+				&new_type);
 	if (IS_ERR(to)) {
 		error = PTR_ERR(to);
 		goto exit1;
@@ -4473,34 +4471,40 @@ static int do_renameat2(int olddfd, const char __user *oldname, int newdfd,
 	if (retry_estale(error, lookup_flags))
 		should_retry = true;
 	path_put(&new_path);
-	putname(to);
 exit1:
 	path_put(&old_path);
-	putname(from);
 	if (should_retry) {
 		should_retry = false;
 		lookup_flags |= LOOKUP_REVAL;
 		goto retry;
 	}
-exit:
+put_both:
+	if (!IS_ERR(from))
+		putname(from);
+put_new:
+	if (!IS_ERR(to))
+		putname(to);
 	return error;
 }
 
 SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
 		int, newdfd, const char __user *, newname, unsigned int, flags)
 {
-	return do_renameat2(olddfd, oldname, newdfd, newname, flags);
+	return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname),
+				flags);
 }
 
 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
 		int, newdfd, const char __user *, newname)
 {
-	return do_renameat2(olddfd, oldname, newdfd, newname, 0);
+	return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname),
+				0);
 }
 
 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
 {
-	return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
+	return do_renameat2(AT_FDCWD, getname(oldname), AT_FDCWD,
+				getname(newname), 0);
 }
 
 int readlink_copy(char __user *buffer, int buflen, const char *link)